Provided by: iproute2_4.15.0-2ubuntu1.3_amd64 bug


       fw - fwmark traffic control filter


       tc filter ... fw [ classid CLASSID ] [ action ACTION_SPEC ]


       the fw filter allows to classify packets based on a previously set fwmark by iptables.  If
       it is identical to the filter's handle, the  filter  matches.   iptables  allows  to  mark
       single  packets with the MARK target, or whole connections using CONNMARK.  The benefit of
       using this filter instead of doing the heavy-lifting with tc itself is that on one hand it
       might  be  convenient  to  keep packet filtering and classification in one place, possibly
       having to match a packet just once, and on the other users familiar with iptables but  not
       tc will have a less hard time adding QoS to their setups.


       classid CLASSID
              Push matching packets to the class identified by CLASSID.

       action ACTION_SPEC
              Apply an action from the generic actions framework on matching packets.


       Take e.g. the following tc filter statement:

              tc filter add ... handle 6 fw classid 1:1

       will match if the packet's fwmark value is 6.  This is a sample iptables statement marking
       packets coming in on eth0:

              iptables -t mangle -A PREROUTING -i eth0 -j MARK --set-mark 6


       tc(8), iptables(8), iptables-extensions(8)